Hi All,
I am writing to seek advice on doing sulphur SAD data collection
at Cu based home source for a protein that is 12 KDa and has 6 S atoms.
I have seen some links online and some references but would be grateful if
you can share your know-how for success with this.
Like what multiplicity of
Well - the S f" is only ~ 0.5 at Cu Kalpha so the signal will be very
weak..
Very accurate data may get a solution but you first have to position the S
atoms...
Much easier to try to make a heavy atom derivative!
Eleanor
On 3 April 2018 at 15:26, Manoj Saxena <
1d16aa30e8a1-dmarc-requ...@jis
Dear Manoj,
providing your crystals diffract to at least 2.5 Å and the sulfurs are
ordered, you should be able to solve your structure without too many
problems. As a first experiment, I would recommend collecting 360 degrees
of data. Process these with XDS and the FRIEDEL'S_LAW= FALSE option an
Iodine is ideally suited for Cu K-alpha SAD phasing, and iodide ions can
normally be easily added by soaking crystals in potassium iodide
containing solutions, which can be done at the time of cryopreservation.
A quick lit search will turn up the appropriate protocols. For
structural genomics w
: CCP4 bulletin board On Behalf Of Eleanor Dodson
Sent: Tuesday, April 3, 2018 20:17
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] Sulphur SAD at home source
Well - the S f" is only ~ 0.5 at Cu Kalpha so the signal will be very weak..
Very accurate data may get a solution but you first ha
Thank you!, Andreas and all others who replied.
I have seen your tutorial and that's what I was referring to.
Maybe I can consult you later when I screen some samples and have an idea
of signal strength?
Regards
Manoj
2018-04-03 10:55 GMT-04:00 Andreas Förster :
> Dear Manoj,
>
> providing you
separate so that the anomalous differences can be used to find
> positions of the S atoms.
>
>
>
> Hope that helps,
>
> Raghu
>
>
>
> *From:* CCP4 bulletin board *On Behalf Of *Eleanor
> Dodson
> *Sent:* Tuesday, April 3, 2018 20:17
> *To:* CCP4BB@JISCMA
Dear Manoj,
I'm happy to answer your questions and have a look at your data. Maybe we
can take this off-list and you report back if and when you solve your
structure.
By the way, I'm processing native data collected with a MetalJet at the
moment. The anomalous signal is even weaker at 1.35 Å bu
: Re: [ccp4bb] Sulphur SAD at home source
Iodine is ideally suited for Cu K-alpha SAD phasing, and iodide ions can
normally be easily added by soaking crystals in potassium iodide containing
solutions, which can be done at the time of cryopreservation. A quick lit
search will turn up the
Hi Manoj,
it depends on crystal and hardware (detector, beam, goniometer) quality as well
as on the correct strategy whether you will be able to solve the structure with
sulfur SAD. 6 sulfur in 12 kDa should be doable, if the crystals diffract to
2.5A or better. Others have given good advice or
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